Existing indicators of agricultural protection and support were developed primarily to gauge the market and welfare effects of government policies. They have shed light on a wider range of impacts through their use in economic models and empirical analysis. The rising scale of support to agriculture globally, and continued reliance on market distorting policy instruments, make this work as important as ever. Deeper investments are nonetheless needed to address heightened concerns about the spill‐over impacts of agricultural policies on the performance of food systems, in particular with respect to food security and nutrition, rural livelihoods, resource use and the environment, and global emissions. A first area for development is improved measures of policies to correct agriculture's externalities. A priority here is to develop a carbon tax equivalent of sectoral mitigation efforts. A second area is to provide a clearer delineation of government spending on private versus public goods. This would make a valuable contribution to a ‘repurposing’ agenda that seeks to identify how agricultural budgets can be spent more effectively, as well as the scope for transferring resources to wider social priorities, such as public health and climate action.